biological molecules

Question 1

What are carbohydrates (made from simple sugars) and lipids (made from fatty acids and glycerol) made of?

Answer 1

carbon, hydrogen and oxygen

Question 2

What are proteins (made from amino acids) made of?

Answer 2

carbon, hydrogen, oxygen, nitrogen and sometimes sulphur

Question 3

starch and glycogen are types of carbs, what are their functions?

Answer 3

starch: used by plants when they have a surplus of glucose, made in photosynthesis

glycogen: used by animals for surplus glucose
- found in liver and muscle tissue

starch and glycogen are large polymer molecules made of GLUCOSE (a simple sugar).

Question 4

fatty acids and glycerol (lipids ), functions

Answer 4

make cell membranes, insulation, protection of organs and act as a store of energy.

FATS and OILS (lipids) are made from fatty acids and glycerol.

one glycerol has three fatty acids attached to it.

Question 5

Proteins uses

Answer 5

Proteins are used for growth, and muscle repair.

Proteins are made up of amino acids(monomers) joined together.

Different amino acids bond together, to form chains known as peptides. The bonds between these amino acids are known as peptide bonds. These peptides come together to form proteins such as enzymes.

• the bonds are weak, and after a certain temperature the enzymes start to denature

Question 6

Iodine test for starch
- carbs

Answer 6

All that needs to be done is adding a few drops of iodine to the test solution/ test material.

• If it contains starch, the solution will turn blue-black
• if not, it’ll remain an orangey/ brown colour (colour of iodine).

Question 7

Benedict’s solution to test for reducing sugars (glucose)
- carbs

Answer 7

Add food to a boiling tube

Then add Benedict solution into the boiling tube, which is a blue colour.

Then you need to heat it up the boiling tube INSIDE a WATER BATH at 80^C for around 5 minutes.

glucose will change colour of substance (the colour will range from how much glucose is inside)

IN THIS ORDER:

No glucose = blue
- GREEN
- YELLOW
- ORANGE
- RED (high level of glucose)

Question 8

biuret test for proteins

Answer 8

Add Biuret solution to proteins.

Starts of blue but will turn lilac/purple if protein is present.

Question 9

ethanol emulsion test for fats and oils.
- lipids

Answer 9

• add small volume of ethanol

shake the test tube and the fat (if there) dissolves into the ethanol.

• then add equal volume of water and if cloudy WHITE emulsion forms then fats are present